Sodium polyoxyethylene alkyl ether carboxylates and o-substituted glyceric acid sodium salts have been known as surfactants of ether carboxylate type [The Chemical Society of Japan 1980, No. 9, 1385-1389; Japan Laying-open Patent 1982-162.797; etc.]. However, the former does not have sufficient properties as surfactant in areas of weak acid and alkali, though it exhibits good properties in neutral and weak alkaline areas. The latter has a defect of being too expensive due to its complicated method to prepare.